Floating, mass and shape | Science | Quizalize & Oak National Academy

Starter quiz

Which is the best definition of the weight of an object?
- the amount of material it contains
- the size of force needed to lift or support it ✓
- the space the object takes up
- the resultant force acting on the object
Which is the best definition of the mass of an object?
- the force pulling down on it
- the amount of material it contains ✓
- the total number of atoms inside it
- the amount of space it takes up
The figure shows two forces acting on a toy boat on the surface of water. Which statements are correct?
- the boat will be speeding up ✓
- the boat will be at a steady speed
- the boat will be slowing down
- not all of the forces are shown in the figure ✓
A balance is used to measure the mass of a sample of water. If the mass of the water is 320 g, what is this mass in kilograms?
- 320 kg
- 32.0 kg
- 3.2 kg
- 0.32 kg ✓
- 0.032 kg
A sample of water has a mass of 0.5 kg. What is its approximate weight on Earth?
- 0.05 N
- 0.5 N
- 5 N ✓
- 50 N
- 500 N
This cruise ship is stationary and floating on the surface of the water. Which statements are correct?
- There are no vertical forces acting on the ship.
- There is a downwards gravitational force acting on the ship. ✓
- There is an upwards force acting on the ship. ✓
- There is a resultant force acting on the ship.
- The ship has no weight.

Exit quiz

Match the key words to the explanations
- upthrust
  
  ⇔
  
  A force acting on a floating object due to water pressure. ✓
- displaced
  
  ⇔
  
  Moved away from its normal position. ✓
- displacement can
  
  ⇔
  
  Used to find the volume or mass of displaced water. ✓
- density
  
  ⇔
  
  If this is high an object will sink. ✓
A cargo ship is travelling on water. Which of these statements is correct?
- All of the ship is floating on the water. ✓
- only the part of the ship above the water is floating
- only the part of the ship below the water is floating
- none of the ship is floating
A wooden boat floats in shallow water. Which of these describes what will happen when it is placed in deeper water?
- The boat will sink
- The boat will float higher in the water
- The boat will float lower in the water
- The boat will float at the same height in the water. ✓
Which of these is the correct condition for something to be able to float?
- there is no upthrust acting on it
- its weight is greater than the uptrust
- it can push its own mass of water out of the way. ✓
- it pushes less than its own mass of water out of the way.
The table shows the mass of objects and the mass of water they displace. Which objects float?
- Object A
- Object B ✓
- Object C ✓
- Object D
- Object E
A pupil makes a boat from aluminium foil. It floats on water. When they scrunch it up into a ball it sinks. Why?
- The foil boat floats because aluminium is less dense than water.
- The foil boat floats because aluminium is more dense than water.
- The foil boat floats because the boat's density is less than that of water. ✓
- The ball sinks because its density is lower than that of water.
- The ball sinks because its density is higher than that of water. ✓

Worksheet

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Lesson Details

Key learning points

The whole of an object is floating on water if part of it is above the surface.
How well an object floats in a liquid does not depend on the depth of the liquid.
An object floats in water if its shape can push its own mass of water out of the way without going under.

Common misconception

Pupils may think that all light objects float and that all heavy objects sink.

Explore how mass and volume (determined by shape) affect whether objects float or sink - before discussing density.

Keywords

Upthrust - A force acting upwards due to pressure is an upthrust.
Displaced - Water is displaced (moved) when an object floats on it or sinks in it.
Displacement can - A displacement can is used to find the volume of water displaced by objects when they float or sink.
Density - If the density of an object is less than the density of water, it will float.